Fuel control apparatus for internal-combustion engines



Feb. 2, 1954 L 2,667,743

FUEL CONTROL APPARATUS FOR INTERNAL-COMBUSTION ENGINES Filed April 25, 1946 TO GEARS42 FUEL PUMP T0 TURBINE INVENTOR.

SHAFT LEIGHTON LEEIE AGENT Patented Feb. 2, 1954 FUEL' CONTROL APPARATUS FOR INTER- NAL-COMBUSTION ENGINES Leighton Lee II, Rocky Hill, Conn., assignor,'- by mesne assignments, to 'Niles Bement-Pond Company, West Hartford, Conn., a corpora.-

tion of New Jersey Application April 23, 1946, Serial No. 664,411

22 Claims. (Cl. Gil-39.28)

The present invention applies to fuel control apparatus for internal cembustion engines of the turbo-jet type, including gas turbine engines, jet engines, and combination gas-turbine-and-jet engines.

The particular embodiments of the invention herein disclosed are intended for control of fuel delivery to an internal combustion engine of the turbo-jet type suitablefor propeller-propulsion, jet-propulsion, or combined propeller-and iet propulsion of aircraft. Such engines usually include one or more combustion chambers, a compressor for supplying air to the combustion chambers, a fuel pump for supplying fuel to the combustion chambers, a gas turbine operated by the products of combustion from the chambers, and a tail pipe for discharging the gases from the turbine.

Owing to structural and metallurgical limitations of such engines, it is necessary to limit fuel flow to prevent speeds or temperatures in excess of predetermined values. The significance of the fuel-to-air ratio applying to reciprocating engines is less apparent in gas turbine engines, owing to the need of speed and temperature controls and the fact that relatively lowvalucs oi the fuel-to-air ratio are employed. Nevertheless, gas turbine engines'have definite fuel requirements, which are determined to some extent empirically, and mechanical means for satisfying such requirements must be developed.

An object of the present invention is toprovide improved apparatus'ior controlling the supply of fuel to a gas turbine or turbo-jet engine.

Another object of my invention is to provide improved control apparatus for an internal cornbustion turbo-jet engine wherein a high pressure region of the engine is used as a source of iiuid under pressure for operating a pressure responsive fuel flow controlling device, and the pressure o'f'the fluid from that source may be modified in accordance with various other controlling ccnditions before the fluid is applied to said fuel now controlling device.

It is further object of my invention to provide improved apparatus for regulating fuel flow as a function of an air pressure derived from air pressure differential which in'turn is function of engine speed, air density, and com ressor characteristics.

Another object of my invention is to provide in control apparatus of the type described, im proved means for limiting 'rfuel'flowso that predetermined engine speed and temperature limits will not be exceeded.

A'further object of my invention is-to provide, in an engine of the-type described, improved means whereby auxiliary combustion meansin the engine is made operable when predetermined conditions of engine operation exist.

A stillfurther object of the present invention is to provideimprovedifuel control apparatus-of simplified design in which an hydraulic motor for controlling pump delivery is operated by the pump discharge pressure so as to be self 'regulat Other objects and advantages'rof the present invention will become apparent'from a consideration of the appended specification claims, and drawing, in which the figure illustrates, some-j what diagrammatically; one form of-fuel control apparatus embodying the'principles ofmy invention and its relation to the engine.

Referring to thedrawing'thereis shown diagrammatically an internal combustion engine of the turbo-jet type connected to a'iuelcontrol apparatus. "Principal elements'of the'engine include an air inlet 'l'ii, a multi-stage'air' compressor generally indicated at 1'2 and a combustion chamber I4 supplied with fuel thrua series of nozzles l6 which are-connected to a fuel manifold [8 into which'the fuel is supplied thrua conduit '20 connected'tothe' fuel control apparatus. An'auxiliaryiuel manifold 22 to which fuel is supplied'by an auxiliaryiul conduit24 is con-' nected to one or more auxiliary nozzles similar to nozzles I6 in combustion chamber M. 'Thus'con duitszfi and 2ll-supply'fuel to separate parallel nozzles. Gases leaving the combustionchamber l4 enter'a. turbine generally indicated'asZG an'd are discharged'fromthe engine thru a tailpipe 28. A revolving shaft 30' is supported by acenter bearing 32 'and'by en'd'bearings '34 and 36 -respectively-at the outer'en'ds'of the compressor rotor 38 and theturbinerotor 40.

'A spee'd're ducing geartrainAZ connects the turbine shaft auxiliary valve mechanism 56, for flow of fuel to the auxiliary manifold 22. The fuel control apparatus regulates the pressure differential across orifice 52 and thereby the total fuel flow to the engine thru both main and auxiliary systems.

In the fuel control apparatus, there is shown a regulator generally indicated at 58 to which air is delivered from the discharge side of the compressor I2 thru a conduit 66, a thermal valve mechanism generally indicated at 62, a conduit 64, the governor mechanism 48, and a conduit 66. In the arrangement shown, air flows from regulator 58 thru a conduit 68 to a manually operated valve mechanism 10, thence either to atmosphere through a port I4, or alternatively, through a conduit '12 which is connected to air inlet I of the engine, upstream of compressor I2.

Regulator 58 has a generally cylindrical body in the ends of which are two symmetrically disposed chambers 16 and 18 which are separated by a centrally located constriction in said body, slidable in which there is a valve 80 having its ends extending into chambers and I8 respectively. A movable plate 79 is fixed to the upper end of valve 80 and is attached to the lower and upper ends respectively of two bellows 82 and 84. The upper end of bellows 82 is fixed to the upper end of chamber 16, and the lower end of bellows 84 is fixed to the lower end of chamber 16. A sealing bellows 38 is mounted between plate 19 and the lower end of chamber 6, paralleling bellows 84 and forming therewith a chamber 81. A spring 86 is retained in compression between the plate I9 and the lower end of chamber 16. Conduit 66 is connected to the interior of bellows 82, the pressure in which is therefore the compressor discharge pressure whenever unrestricted fiow occurs from conduit 60 to conduit 66. Chamber I6 is supplied with air flowing from conduit 66 thru a restriction 90 in a conduit 92. The pressure on the exterior of bellows 82 and 84 is that of air in chamber I6 and is therefore atmospheric pressure whenever unrestricted flow occurs from chamber 16 to conduit I2. Bellows 84 may either be evacuated or filled with a temperature responsive medium at a predetermined pressure and sealed before installation thereby rendering bellows 84 responsive to temperature and pressure changes in chamber 16.

In chamber 18, a bellows 94 is mounted between the lower end of valve and the lower end of chamber 78. A conduit 96 connects the interior of bellows 94 to conduit 58 and a conduit 98 connects the chamber 18 to conduit 29, thereby rendering bellows 94 responsive to the fuel pressure differential across metering orifice 52.

In equilibrium, the upward force on valve 80 due to the fuel pressure differential acting on bellows 94 equals the net downward force at the upper end of valve 80, comprising forces due to air pressure differentials acting on bellows 82 and 84 and an upward force due to spring 86. At constant temperature and pressure in chamber IE, only the forces produced by bellows 82 and 94 vary, and therefore valve 89 is in equilibrium Whenever the ratio between the air pressure dif ferential acting on bellows 82 and the fuel pressure differential acting on bellows s4 is a predetermined constant. Thus, when the flow of air to and from regulator 58 is unrestricted and the temperature and pressure in chamber 76 are constant, the fuel pressure difierential across metering orifice 52 is proportional to the compressor discharge pressure.

There is provided in the pump 45 a suitable means for varying the pump delivery, which may be of any conventional form such as that disclosed in U. S. Patent 2,093,477, Sept. 21, 1987, and is operable by a lever I00. A hydraulic motor, generally indicated at I02, has a piston iii l connected to lever 2% by a link I136. The piston I04 separates two expansible chambers I08 and H9. Chamber H0 is supplied with fuel at the pump discharge pressure by a conduit H8 connected to another conduit i2ii which in turn is connected to conduit 50. Chamber ms is supplied thru a conduit I3 with fuel at a motor pressure from regulator 58. A spring I I4 imposes a downward force on piston Hi4 and biases the delivery varying means toward maximum delivery position. As the motor pressure increases, pis ton I04 is moved downward in opposition to the pump discharge pressure in chamber I it, thereby increasing the pump delivery and hence the discharge pressure until a position of equilibrium is obtained. Thus, the pump delivery and the pump discharge pressure are functions of the motor fuel pressure in conduit I13, and increase as the motor pressure increases.

Valve as shown is one of a number of conventional forms which may be used and includes a recess H6, a port at the upper end of conduit 26, and a similar port at one end of a drain conduit H2 the other end of which is connected to inlet conduit 45. Both ports are closed when valve 80 is in its normal position. The pressure in conduit H2 is substantially constant; and, when valve 80 is in its normal position, the pump delivery is substantially constant. On downward movement from the normal position referred to, valve 80 permits fuel to flow from conduit 50, thru conduit I 20, to conduit H3 and into chamber 208. Upon upward movement from the normal position, valve Bil permits flow from chamber I08, thru conduit H3, to drain conduit H2, and thence to the pump inlet conduit 45.

Thus as valve 80 moves in a downward direc tion, as when the compressor discharge pressure acting on bellows 82 increases, the motor fuel pressure increases, and the pump delivery increases and hence the pump discharge pressure increases. Conversely, as valve 80 moves in an upward direction, as when the compressor discharge pressure decreases or the fuel pressure differential across metering orifice 52 increases, the motor fuel pressure decreases, and the pump delivery and hence the pump discharge pressure decreases.

The fuel pressure differential across metering orifice 52 is normally proportional to the compressor discharge pressure in conduit fill which acts on bellows 82, and the fuel flow is therefore a predetermined constant function of the compressor discharge pressure. As previously stated. this applies only at normal operating speeds and temperatures, when air lines to and from regulator 58 are unrestricted, and when auxiliary conduit 24 is inoperative.

The thermal control 52 comprises a tube I22 having its upper end closed, the control being so mounted that a portion of the tube extends into the engine where it is subjected to temperature of the gases in tail pipe 28. The other end of tube I22 is retained by a body I24 having an aperture I28 therein for passage of a rod I26 therethru, the upper end of rod 526 being fixed to the closed end of tube I22. The lower end of rod I26 bears a valve I32 which is operable in a seat 238 in body I24, seat I38 separating chambers' l 3 I and I 33- upstream and downstream from valve 132 which are connected to conduits 653 and "64 "respectively. The rod I 26 and tube 1-22 are 1 made of materials having substantially different coefiicients of therrnal expansion, so that, upon an increase in temperature adjacent tube I22, the tube expands faster thanrod T I leg-thereby moving the valve I32 toward closed position and restrictingflow from 'conduit'tfl "toconduit 64. 'By "proper construction an'ddimensions 'of the parts, ithe'th'ermal control may be-made'ineflective to control thefiow=ofair therethruexcept within a relatively narrow range o'f tempera-- ture .7 near :the predetermined limitin temperature.

The governonmec'hanism "48 has a body 59 and employs a conventional Lily-weight governor I2 9 operated from "the gear train 32 in the I engine. EtLis .normally mounted' in a position-at rigiangles to that shown. L n fextension of bod-y 49 has'an opening'therethr-u which serves as a guicle for a "governor "valve 134. A 1 contoured portion of'valve 134 moves in a seat lefithereby varying'the flow of air from'conduited to conduit 66 which conduits are'respectivelyconnectedto hody 'w on opposite'si'des of seat I36. A sprine' 'I3B'is'p1aced between one end of valve lileand a support I which is: slidable in body lll. The other end of valve 'I 34 is 1 connected to the gOV- ernor I29 so that'valve l3 l'moves toward the right in opposition tospring I38 "and restrictsnthe flow from conduit 64 to conduit as the gov- .ernor speed increases. A s-channel I35 is used I to equalize pressures 'atttheends of valve l34. It-is thus apparent that as the governor speed' varies and, I hence as the engine speed-varies, valve its varies the flow-from conduit :64 to conduit e6,

this flow decreasing as the engine speed increases. The rate of change of'flow across valve I34 "in respect'to engine'speedchange'is' controlled by properly contouringthe-valve.

'In'valve'rnechanismfiil thereis'a valve fl, in a valve body '13, the valve being operable in a seat "I'5 to vary the'flow from conduitifiil -to con- 'duit I2 or'part M. Valve 'I'I :isconnecte'dto a manually-operated lever TI and is also connected to slidable spring-support IAO' in governor-meow anism lfi,'byimeans of a linkislancha lever 83 which is-pivoted ata fiXed'support'--8'5. In operation, as valve TI is moved toward its "seat, slidable spring support I'M is moved z-away from valve I34 thereby decreasing the spring force acting .on valve i134 and allowing1itto11noveatoward seat 136 and to'further decrease flow from "conduit M to conduit 66.

vThe auxiliary valve'mechanism "55icomprises2a body I42 having-a chamber 'l s lto-ithealeft-hand end of Which'is fixed "oneend oi? afbellows Jlii. .Movem-ent'of the freeend of bellows I-firiszopposed'by'a spring M8,:having oneaend supp'orted by the bellows and-the otherend by' thezri'ghthand "end of chamber I144. -The interior'rof bellows Mfi is connected by conduit Ielto-thetinte rior of regulator 58 at a source of motor'prelw sure. An extension-of body I42 iszprovided with a cylinder I59 which-serves asta guidezforrarpiston valve i 52 having one end fixed to the: movable endof bellows 145. The'body M2 isepertured to connect conduits 2'4 and 4 5%" with cylinder and. valve I52 has a groovedportion-IE/l nearits mid-portion which-is operable topermit restricted flowfrom conduit 5% toconduit-fid as valve I52 moves toward the right. ;A conduit 4:56 serves as :a'vent :for :cylinder I at rthe ='encl' of valve I52 andz'may "be'lconnectedito 'inlet 'conduit 3 which thermal control 62 is effective.

pressure in chamber I4'4 with lthat in conduit I56. ValVeISZ is'positionecl by a force produced by the motor pressure acting "on *bellows I'4'5 tending to open the valve, and by-spring I48 which tends to I close it. The spring is selected to keep the valve closed below a predetermined value 'of-rnotor pressure.

In operation, l the bellows 82 in regulator '58" is subject to an elrectiveair pressure "diiierential whichis the differential between compressor-dischargeaand atmospheric pressures, when the flow of air to and from the 'regulator is'unrestricted. When the pressure and temperature in chamber Z0 is a function r of this e'ffective air pressuredit"- ferential. To prevent excessive tail pipe temperature, it is necessary 1 to reduce the fuel-flow when a predetermined limiting temperature Zis reached; this is done bymeanso'fthermal-nontrol 52 which reducesthe flow of'air from conduit (50 to conduit 64 andthereby reduces theeffective :air pressure differential acting in regulator 58, as the temperature increases to a valueat Similarly, toprevent excessive-engine speed, it is necessary to "reduce the fuel flow when a predetermined limiting speed is reached; 'thisis done'bymeans of the speed governor mechanism 58 which reduces' the flow from conduitfi l to conduit 6.6 and thereby reduces the eiiectiveair :pressure: differontial in regulator 55, as the-speed increases to a value which the governor mechanism is effective.

'Manual control: or the-effective air pressuredifferential is accomplished by: valve mechanism 1-8. In this case, the iiow'ofairirorn 'regulator'iil is controlled. the e'ilective air pressure differential and hence the" fuel fiow decrease as valve 1I closes, in the'saine manner thatthe effective differential and the fuel fiow decrease as either valve 132 or valv'e I M-closeso flhe :governor mechanism 48 and manuallycontrolled valve mechanism i -0 are connected, so that when -lever-fl is operated itsetsthe governor valve spring I38-so that -the governorbecomcs efiective at a predetermined value'corresponding to the position of lever 1?. simultaneously; 5 the movement of lever T? produces a change in-the position =of valve i I in respect to 'its seat '15, so that the= predetermined limiting value of speed is :increased, as i by increasing" lthe load of spring 1 33 on valve I3 3, theeffective air pressuredifferential is increaserl iby rnoving valve 'i I towarcl its open position. -The connection between the governor and the manual valve mechanism is for :the purpose of limiting fuel flow to. a fixed amount less than Tue! -'flo-w requir.ed to produce limiting temperature at any value thruout the range of i'manual speed control. To accomplish this *purpose, the "design :of: governor me'chanism 43 and :that of -valve :mechanism ill are ecordinated in reference to such factors as valvecontours,rspring1rates,governor characteristics, and linkage.

An :additional "temperature effect is produced hykbnllows 85 which tends' to raise valve 88* as the temperature in chainher- 15 increases, "thereby reducing the motor pressure and the fuel flow. This supplementary temperature control is in 'e'iieetsav means whereby the compressor discharge LDIESSHIB is temperature corrected s o 'that the fuel flow is m'oreinearly a iunctionof the-mass rather than tho velocity"offiair iiowing thru the: engine. ssupplementing 'the main iful -"now thi d son- 7' duit 20, auxiliary valve mechanism 56 provides means of causing flow to the auxiliary fuel manifold 22 when a predetermined value of motor pressure or when a predetermined value of main fue1 flow is attained.

In the foregoing illustrated and described embodiment of my invention, expansible bellows are employed for converting pressure differentials to working forces; in the appended claims, however, the term bellows is used in a general sense which embraces collapsible pressure-responsive elements such as diaphragms, movable pistons, or other suitable equivalent means.

While I have shown and described a preferred embodiment of my invention, it will be readily understood by those skilled in the art that other modifications may be made without departing from the scope of the invention as defined in the appended claims.

-I claim as my invention:

1. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel conduit and a source of fuel at superatmospheric pressure, for delivering fuel to said engine, and means for varying the delivery from said source to said fuel conduit, comprising: hydraulic motor means responsive to a control air pressure derived from the difference between a plurality of fluid pressures in said engine, and means responsive to the speed of said engine for modifying said control air pressure whereby the fuel flow is a function of said difierence in fluid pressures and said speed.

2. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel conduit for delivering fuel thereto, a source of fuel at superatmospheric pressure, and means for varying the delivery from said source to said fuel conduit, comprising: hydraulic motor means responsive to a control air pressure derived from the difference between a plurality of fluid pressures in said engine, and means responsive to the temperature of exhaust gases in said engine for modifying said control air pressure, whereby the fuel flow is a function of said difference in fluid pressures and said temperature.

3. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel conduit and a source of fuel at superatmospheric pressure, for delivering fuel to said engine, and means for varying the delivery from said source to said fuel conduit, comprising: fluid motor means responsive to a control air pressure derived from the difference between a plurality of fluid pressures in said engine, and manually-operated means for modifying said control air pressure whereby the fuel flow is a function of said difference in fluid pressures and said manual modification.

4. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and conduit for delivering fuel thereto, said pump having delivery varying means associated therewith, comprising: hydraulic motor means responsive to fluid pressure supplied thereto and effective to control said delivery varying means, a metering orifice in said fuel conduit and means connected to said conduit effective to regulate said motor fluid pressure in response to the fuel pressure differential across said metering orifice and to an air pressure differential at least one component of which is derived from a pressure in said engine; whereby the fuel flow varies as a function of said air pressure in the engine.

, -5-. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and conduit for delivering fuel thereto, said pump having delivery varying means associated therewith, comprising: hydraulic motor means responsive to a motor fluid pressure supplied thereto effective to control said delivery varying means, a metering orifice in said fuel conduit, means connected to said conduit effective to regulate said motor fluid pressure in response to the fuel pressure differential across said metering orifice and to an air pressure differential at least one component of which is derived from a pressure in said engine, and means for modifying said air pressure differential responsive to the speed of said engine, whereby the fuel flow varies as a function of said speed and said engine pressure.

6. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and conduit for delivering fuel, thereto, said pump having delivery varying means associated therewith, comprising: hydraulic motor means responsive to a motor fluid pressure supplied thereto effective to control said delivery varying means, a metering orifice in said fuel conduit, means connected to said conduit effective to regulate said motor fluid pressure in response to the fuel pressure differential across said metering orifice and to an air pressure differential at least one component of which is derived from a pressure in said engine; and means for modifying said air pressure differential in response to the temperature of exhaust gases in said engine, whereby the fuel flow varies as a function of said temperature and said engine pressure.

7. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and conduit for delivering fuel thereto, said pump having delivery varying means associated therewith, comprising: hydraulic motor means responsive to a motor fluid pressure supplied thereto effective to control said delivery varying means, a metering orifice in said fuel conduit, means connected to said conduit effective to regulate said motor fluid pressure in response to the fuel pressure differential across said metering orifice and to an air pressure differential at least one component of which is derived from a pressure in said engine; and manually-controlled means for modifying said air pressure differential, whereby the fuel flow varies as a function of said manual control and said engine pressure.

8. Fuel control apparatus for a turbo-'-jet engine, having associated therewith a fuel pump and conduit for delivering fuel thereto, said pump having delivery varying means associated therewith comprising: hydraulic motor means responsive to a motor fluid pressure supplied thereto effective to control said delivery varying means, a metering orifice in said fuel conduit, means connected to said conduit effective to regulate said motor fluid pressure in response to the fuel pressure differential across said metering orifice and to an air pressure differential at least one component of which is derived from a pressure in said engine; first and second means respectively for modifying said air pressure differential in response to engine speed and the temperature of exhaust gases flowing thru said engine, and manually-controlled third means for modifying said air pressure differential, whereby the fuel flow varies as a function of said engine air pressure, said speed, said temperature, and said manual control.

9. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and conduit for delivering fuel thereto, said pump having delivery means associatedtherewith, comprising: hydraulic motor means responsive to a motor fluid pressure supplied there to effective to control said delivery varying means-a metering orifice in saidfuel conduit, 21 first bellows responsive to the fuel pressure differential across said orifice, a second bellows responsive to an air pressure differential at least one-component of which is derivedfromlsaid engine, a value operated by said first and second 'be'l-- lows for regulating said motor pressure, whereby the. fuel pressure differential. across said orifice .and' hence the fuel flow to the engine a-refun'ctions ofsaid air pressure differential.

10. Fuel control apparatus for a turbo-jet engine, having associated therewith a source of fuel at superatmospheric pressure, a conduit for con.- veying fuel from said source to said engine. and means for varying the fuel delivery from said source to said conduit, comprising: conduit means for deriving an air pressure differential from an air pressure in said enginegnreans regulating said delivery varying means in response to said air pressure differential; first means in said conduit means responsive to the speed .of said engine and effective to modify said air pres sure differential, and a manually-operated control in said conduit means effective to modify said air pressure differential inzseries with said first modifying means, whereby the fuel flow varies asa functionof said engine pressure differential, said speed, and said manual control.

11. Fuel control apparatus for a turbo..-jet engine, having associated. therewith a source of fuel at superatmospheric pressure, aconduit for conveying fuel from said source .to said engine and means for varying the fuel delivery from said source to said conduit,.comprising: conduit means for deriving an air pressure differential from an air pressure in said enginepmeans regulating saiddelivery. varying means in response to said air pressure differential; first means in said conduit means responsive to the speed of said engine and efiective to modify said air pressure differential, and second means in said conduit means responsiveto exhaust gas temperatures in sai'd engine andeffective to modify said air pressure differential, said first and second modifying means being in series, whereby the. fuel flow I varies as .afunction of said engine pressure, .said speed, and said temperature.

12. Fuel control apparatus for a turbo-jet engine, having associated therewith a compressor for delivering combustion air thereto, a sourcezof -fuel at superatmospheric pressure, a conduit for conveying fuel from said source to said engine and means for varying the fuel delivery from said source to said conduit, comprising: conduit means for deriving an air pressure differential from an air pressure in saidcngine; means. regulating said delivery varying means inresponse to said-air pressuredifferential; first valve means said conduit means for modifying the high pressure component of said air pressuredifferential in response to the temperature of exhaust gases in said engine, second valve means in said conduit means responsive to the-engine speed for modifying the high pressure component of said differential, fixed means in said conduit means for controlling said differential, and third valve means in said, conduit means manually-operated to modify said differential, said'first and second valve modifying means, said fixed means, and saidthird valve modifying means being in series,

10 whereby the fuel flow varies as a function .ofsaid engine pressure and saidfourmodifying means.

13. Fuel control apparatusfor .aturbo-jet .engine including an air compressor, and hay-ingessociated with said enginea fuel pump and conduit for delivering fuel thereto, said pumphaving delivery varying means associated therewith, comprising: hydraulic motor means responsive to a motor fiuidpressure suppliedthereto efifeative to control said delivery varying means, cone duit means for deriving. anair pressureldifferential from the compressor dischargev pressure. in said engine, valveineans regulating said delivery varying means in response tosaidair pressure diffv .ential, first means for modifying saiddifferential in response to the temperature of ex.- haust gases in the engine, a speed governor, valve means responsive to said. governor and fixed means for controllingsaid differential and man.-

gine having therein main and auigiliar-y burners and having associated therewith main and aux.- iliary fuel conduits respectivelyfor delivery of fuel to said main and auxiliaryburners, a compressor for delivering combustion air :to said ongine, a fuelpump and means for varying the .delivery thereof, and a connection between said pump and said. main and auxiliary .conduits, .comprising: conduitmeans for deriving an air pressure differential from the compressor pressure differential in said engine, a metering orifice in said main conduit, hydraulic motor means for controlling said delivery varying means in response to a motor fluid pressure supplied thereto, valve means for regulating. said motor pressure in response to said air pressure :dffferentiahend to the fuel pressure differential across. said metering orifice; at least two variable orifices .in series in said conduit means effective to modif said air pressure differential; andsecond means responsive to said motor pressure effective. to connect said auxiliary fuel conduit to said main fuel conduit downstream from said orifice when said motor pressure exceeds a predetermined: value, whereby the total fuel flow varies as afunction of said-compressor pressure differential, said variable restrictions in series and-said second conduit connecting means.

15. Fuel-control apparatus for a turbo-jetengine including a tail pipe, and having associated with said engine a fuel conduit, a fuel pump-and means for varying the delivery of said pump to said conduit, comprising: conduit means for deriving anair pressure differential from a pressure in said engine, aineter-ing-orifice in saidafuelconduit, an hydraulic motor effective :to regulatesaid delivery varying means in response to a-motor fluid pressure supplied thereto, valve means for regulating said motor pressure responsive to :said air pressure differential and'to the fuel pressure differential-across said orifice, fixed means in=said conduit means for controlling said air pressure differential effective to control the rate of response of-said regulating means to said modified airpressure differential, and first and second valve means in said conduit means inserieswi-th Fsaid'fixed means effective to modify said air pressure differential in response to the speed of said engine and the temperature of gases in said tail pipe, whereby the fuel flow varies as a function of said engine pressure, said fixed controlling means, said engine speed and said tail pipe temperature.

16. Fuel control apparatus for a turbo-jet engine, including a tail pipe and an air compressor and having associated with said engine a fuel conduit, a fuel pump and means for varying the delivery thereof, and a connection between said pump and said conduit, comprising: hydraulic motor means responsive to a motor fluid pressure supplied thereto and effective to control said delivery varying means; conduit means for deriving an air pressure differential from the compressor pressure differential in said engine; an air bleed in said conduit means subjected to said air pressure differential, valve means regulating said motor pressure in response to said air pressure difierential; first valve means upstream from said bleed for controlling the flow of air in said conduit means in response to the temperature of gases in said tail pipe, a governor connected to said engine, governor-valve means in series with said first valve means and upstream from said bleed for controlling the flow of air in said conduit means in response to said governor, a spring effective to regulate said response of said governor-valve to said governor, and a variable support for said spring; a manually-operated valve downstream from said bleed in said conduit -means effective to control the flow of air therethru; and a connection between said governor spring support and said manually-operated valve; whereby the fuel flow varies as a function of said compressor pressure differential, the tail pipe temperature, the engine speed, and said manual control.

17. Fuel control apparatus for a turbo-jet engine, having associated therewith first and second fuelconduits and a compressor respectively for delivering fuel and combustion air thereto, and having also associated therewith a fuel pump and means for varying the delivery thereof, connections between said pump and said first and, second conduits, and a tail pipe, comprising: a metering orifice in said first conduit, hydraulic motor means responsive to a motor fluid pressure supplied thereto and effective to control said delivery varying means; conduit .means for derivng an air pressure differential from the compressor pressure differential in said engine, an air bleed in said conduit means subjected to said air pressure differential, valve means for regulating saidmotor pressure responsive to said air pressure differential and to the fuel pressure differential across said metering orifice; first valve means upstream from said bleed for controlling the fiow of air in said conduit means in response to the temperature of gases in said tail pipe, a governor connected to said engine, governor-valve means in series with said first valve means and upstream from said bleed spring support and said manually-operated valve; .an, auxiliary valve, means responsive to said 12 motor pressure and effective to operate said auxiliary valve, said auxiliary valve being effective to connect said first and second conduits at a point downstream from said orifice when said motor pressure exceeds a predetermined value; whereby the total fuel flow varies as a function of the compressor pressure difierential, the tail pipe temperature, the engine speed, said manual control, and said auxiliary valve.

18. Fuel control apparatus for a turbo-jet engine including a tail pipe and an air compressor, and having associated with said engine a fuel pump and conduit for the flow of fuel thereto, means for varying the delivery of said pump to said conduit, comprising: a metering orifice'iin said fuel conduit, an hydraulic motor effective to regulate said delivery varying means in response to a motor fluid pressure supplied thereto, a tube having its opposite ends connected to pressures in said engine upstream and downstream respectively from said compressor, a fixed restriction for controlling the flow of air therethru, first and second valve means for respectively varying the flow thru said tube in response to the engine speed and the temperature of gases in said tail pipe, manually-operated valve means for varying the flow in said tube in series with said other flow varying means, valve means regulating said motor pressure responsive to the differential between the pressure downstream from said compressor and the pressure in said tube on the upstream side of said manually-operated valve, said regulating valve means being also responsive to the fuel pressure differential across said orifice, whereby the fuel fiow varies as a function of said upstream and downstream pressures and said means for varying the flow in said tube.

19. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and means for varying the delivery of said pump to said engine, comprising; motor means responsive to a motor fuel pressure and to a motor air pressure and effective to control said delivery varying means, said motor fuel pressure being a function of the fuel pressure differential across said pump and said motor air pressure being a function of the difference between a plurality of fluid pressures in said engine, and means for varying said motor air pressure, whereby the fuel flow varies as a function of said fuel pressure differential, said difference in fluid pressures, and said pressure varying means.

20. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and means for varying the delivery of said pump to said engine, comprising: motor means responsive to a motor fuel pressure and to a motor air pressure and effective to control said delivery varying means, said motor fuel pressure being a function of the fuel pressure differential across said pump and said motor air pressure being a function of the difference between a plurality of fluid pressures in said engine, and means for varying said motor fuel pressure, whereby the fuel flow varies as a function of said fuel pressure differential, said difference in fluid pressures and said motor fuel pressure varying means.

21. Fuel control apparatus for a turbo-jet engine, having associated therewith a fuel pump and means for varying the delivery of said pump to said engine, comprising: motor means responsive to a motor fuel pressure and to a motor air pressure and effective to control said delivery varying means, said motor fuel pressure being a function of thefuel pressure differential across said pump and said motor air pressure being a function of the difference between a plurality of fluid pressures in said engine, and means for varying said motor fuel and motor air pressures, whereby the fuel flow varies as a function of said fuel pressure differential, said difference in fluid pressures, said motor fuel pressure varying means, and said motor air pressure varying means.

22. Fuel control apparatus for a turbo-jet engine, including an air compressor, and having associated with said engine a fuel pump and means for varying the delivery of said pump to said engine, comprising: motor means responsive to the compressor discharge pressure in said engine and effective to regulate said delivery varying means, a conduit effective to by-pass fuel therethru around said pump, a restriction in said conduit, a connection for the flow of fuel between said conduit upstream from said restriction to said motor means, thereby rendering said motor means also responsive to the fuel pressure in said connection, whereby the fuel flow varies as a function of said compressor discharge pressure and said fuel pressure.

I LEIGHTON LEE II.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,219,994 Jung Oct. 29, 1940 2,245,562 Becker June 17, 1941 2,341,257 Wi'msch Feb. 8, 1944 2,348,113 Davis May 2, 1944 2,378,037 Reggio June 12, 1945 2,400,415 Hersey May 14, 1946 2,404,323 Staley July 16, 1946 2,404,324 Stale'y July 16, 1946 2,410,774 Chandler Nov. 5, 1946 

